Epson S1D13504 Manuel D’Utilisation

Page 3

Vancouver Design Center

Power Consumption

S1D13504

Issue Date: 01/02/02 

X19A-G-006-04

S1D13504 power consumption is affected by many system design variables.

• Input clock frequency (CLKI): the CLKI frequency determines the LCD frame-rate, CPU perfor-

mance to memory, and other functions – the higher the input clock frequency, the higher the 
frame-rate, performance and power consumption.  

• CPU interface: the S1D13504 IO V

DD

 current consumption depends on the BUSCLK frequency, 

data width, number of toggling pins, and other factors – the higher the BUSCLK, the higher the 
CPU performance and power consumption.

• Core V

DD

, IO V

DD

 voltage levels: the voltage levels of the two independent VDD groups (Core, 

IO) affect power consumption – the higher the voltage, the higher the consumption.

• Display mode: the resolution and color depth affect power consumption – the higher the

resolution/color depth, the higher the consumption.

• Internal CLK divide: internal registers allow the input clock to be divided before going to the 

internal logic blocks – the higher the divide, the lower the power consumption.

There are two power save modes in the S1D13504: Software and Hardware SUSPEND. The power 
consumption of these modes is also affected by various system design variables.

• DRAM refresh mode, CBR or self-refresh: self-refresh capable DRAM allows the S1D13504 to 

disable the internal memory clock thereby saving power.

• CPU bus state during SUSPEND: the state of the CPU bus signals during SUSPEND has a 

substantial effect on power consumption. An inactive bus (e.g. BUSCLK = low, Addr = low etc.) 
reduces overall system power consumption.

• CLKI state during SUSPEND: disabling the CLKI during SUSPEND has substantial power 

savings.